This is a prospective, randomized trial to independently assess the effectiveness of each of the following four regimens as adjuvant treatment for patients with Dukes' B or C colon cancer: (1) 5-Fluorouracil (5-FU) and low dose Leucovorin, (2) high dose Leucovorin + 5-FU, (3) 5-FU + Levamisole and (4) 5-FU, low-dose Leucovorin and Levamisole. ECOG 2288)